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ABSORB II fails to meet 3-year primary endpoints
WASHINGTON — A bioresorbable vascular scaffold did not meet its coprimary endpoint of noninferior late luminal loss or its mechanistic coprimary endpoint of superior vasomotor reactivity vs. an everolimus-eluting stent, according to 3-year results from the ABSORB II trial presented at TCT 2016.
In the randomized, prospective, single blind trial, researchers evaluated 501 patients aged 18 to 85 years with signs of myocardial ischemia and up to two de novo native coronary lesions located in different vessels. Patients were randomly allocated to undergo treatment with a BVS (Absorb; Abbott Vascular; 335 patients; 364 lesions) or an EES (Xience, Abbott Vascular; 166 patients; 182 lesions).
Patrick W. Serruys, MD, PhD, emeritus professor of interventional cardiology at Imperial College London and Thoraxcenter of the Erasmus University Medical Center in Rotterdam, the Netherlands, and colleagues stratified the randomizations by diabetes status and number of intended target lesions. The study’s primary endpoint at 3 years was the superiority of BVS vs. EES in angiographic vasomotor reactivity after administration of intracoronary nitrate. Vasomotion was assessed at 3 years by change in mean lumen diameter pre- and post-intracoronary nitrate. Comparisons for this endpoint were made using a two-sided t test.
Patients also completed the Seattle Angina Questionnaire preimplantation, at 30 and 180 days, and at 1, 2 and 3 years, and underwent exercise testing with ECG: ST-segment depression of ≥ 0.1 mV or chest pain.
Endpoints not met
The coprimary endpoint was noninferiority in terms of late luminal loss, and this endpoint was compared using a one-sided asymptotic test against a noninferiority margin of 0.14 mm.
The researchers found no statistically significant difference in vasomotor reactivity at 3 years (BVS cohort, 0.047 mm vs. EES cohort, 0.056 mm; P for superiority = .49), whereas the BVS device yielded larger late luminal loss at 3 years vs. EES (0.37 mm in the BVS group vs. 0.25 mm; P for noninferiority = .78). IVUS evaluation of the minimum luminal area confirmed this difference in luminal dimension (4.32 mm2 vs. 5.38 mm2; P < .0001). Moreover, no statistically significant differences were seen between the two devices in the secondary endpoints of patient-oriented composite endpoint, Seattle Angina Questionnaire score and exercise testing. However, a significant difference was seen between the two groups in a device-oriented composite endpoint (10% BVS vs. 5% EES; HR = 2.17; 95% CI, 1.01-4.7), prompted in large part by target-vessel MI (6% BVS vs. 1% EES; P = .0108), including periprocedural MI (4% vs. 1%; P = .16).
“Future studies should investigate the clinical impact of accurate intravascular imaging in sizing the device and in optimizing the scaffold implantation,” the researchers wrote. “The benefit and need for prolonged dual antiplatelet therapy after bioresorbable scaffold implantation could also become a topic for future clinical research.”
ABSORB China
Also presented at TCT 2016 were 2-year results of the ABSORB China study, which found generally low and similar rates of device-oriented clinical events between the BVS and the EES stent.
In the prospective, open-label, multicenter study, Runlin Gao, MD, of the Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences, Beijing, and colleagues evaluated 480 patients with up to two de novo lesions in separate arteries who were enrolled from 24 sites in China. Eligible patients had lesion length ≤ 24 mm, reference vessel diameter ≥ 2.5 mm to ≤ 3.75 mm, and percent diameter stenosis ≥ 50% to < 100%. Patients were randomly allocated at a 1:1 ratio to treatment with the BVS (n = 241) or EES (n = 239).
The researchers found that, at 2 years, the study met its primary endpoint of noninferiority in the following outcomes: all-cause death (0.4% BVS vs. 2.5% EES; P = .12), cardiac death (0.4% vs. 1.3%; P = .62), all MI (3% vs. 2.1%; P = .56), target-vessel MI (2.1% vs. 0.8%; P = .45), all revascularization (8.9% vs. 8.4%; P = .87) and ischemic-driven target lesion revascularization (ID-TLR; 3.4% vs. 2.5%; P = .59).
One patient in the BVS group experienced very late stent thrombosis (between 1 and 2 years) and one patient had an early definite scaffold thrombosis < 30 days. Moderate and severe calcification, as well as smoking, were identified as predictors of target lesion failure.
“The rates of clinical events, including TLF, cardiac death, [target-vessel] MI, ID-TLR and device thrombosis were generally low and comparable between ABSORB BVS and Xience V at 1 year,” the presentation stated. “This trend of low event rates and comparable results between treatment arms continued at 2 years.” – by Jennifer Byrne
References:
Gao R, et al. Serruys PW, et al. Plenary Session VI. First Report Investigations 1. Both presented at: TCT Scientific Symposium; Oct. 29-Nov. 2, 2016; Washington, D.C.
Serruys PW, et al. Lancet. 2016;doi:10.1016/S0140-6736(16)32050-5.
Disclosure: Gao reports receiving research grants from Abbott Vascular, Lifetech and MicroPort. Serruys reports consulting for Abbott, AstraZeneca, Biotronik, Cardialysis, GLG Research, Medtronic, Qualimed, Sinomedical Sciences Technology, Société Europa Digital Publishing, Stentys France, St. Jude Medical, Svelte Medical Systems and Volcano.